Transformer.



7 PATENTED DEG.17, 1907. J. GOATBS.

TRANSFORMER.

APYLIOATIOK FILED FEB. 12, 190B.

3 8HEETS'SHEET 1.

Jesse Coates,

J. OOATES. TRANSFORMER.

PATENTED DEC. 17, 1907.

APPLIOATION FILED 33.12, 1906.

3 SHEETS-SHEET 2.

L & b

UNITED STATES PATENT OFFICE.

JESSE OOATES, OF LYNN, MASSACHUSETTS, ASSIGNOR TO GENERAL ELECTRICCOMPANY, A

CORPORATION OJ." NEW YORK.

TRANSFORMER.

Specification of Letters Patent.

Patented Dec. 17, 1907.

Application filed'lebruary 12.1906. Serial No. 300.594.

To all whom it may concern:

Be it known that I, JESSE CoArEs, a citizen of the United States,residing at Lynn, county of Essex, State of Massachusetts,

have invented certain new and useful Imrovements in Transformers, ofwhich the ollowing is a specification.

My present invention relates to stationary electrical transformers ofthe type such as is shown in the patent to Hall, No. 755,766, in

which all of the windings of the transformer surround a central core-legof magnetic material, the ends of the core-le surrounded by the windingsbeing connected by a number of return circuits of magnetic materialwhich pass around the outer surface of the windy invention comprisescertaln improvements in the configuratlon and production of the coreblank laminae, their assembly to form the transformer core, and thearrangement of the eot'iperating windings with 'respect thereto.

The various features of novelty which characterize my invention arepointed out with particularity in the claims annexed to and forming partof this specification. For a better understanding of my invention,however, reference may be had to the accompanyin drawings anddescriptive matter, in

which have illustrated and described forms in which my invention may beembodied.

Of the drawings, Figure 1 is a perspective view illustrating atransformer constructed in accordance with my invention; Fig. 2 is asectional plan view of the transformer shown in Fig. 1; Fig. 3 is a viewsimilar to Fig. 2, SllOWlIl a modified construction; Fig. '4 is a viewil ustrating the method of cutting out 40 certain of the transformercore blanks; Fig.

5 is a view of one of the main E punchings and cooperating end-closingmembers; Fig. 6 shows the punching of Fig. 5 reversed; Fig. 7 shows oneof the main U-punchings and end-closing member; Fig. 8 shows the in Fis. 1 and 2, the transformer core is compose" of a bundle 1 ofE-punchings and suitable end-members, two main bundles 2 of U-punchingsextending from opposite sides of the middle leg of the bundle 1 andcooperating end-members, auxiliary bundles 3 of U-punchings andend-members arran ed one at each side of the bundles 2 and 0t erauxiliary bundles 4 of U-punchings and endmembers also arranged one ateachside of each set of punchings 2.

The laminae composing the bundles 2 and 3 are parallel to each other andat right angles to the laminae of the bundles 1 and 4.

It will be observed that the transformer core comprises a central leg 5about which is placed the high-voltage windings 6 and the low-voltagewindings 1 of the transformer. The central leg of the transformercomprises the middle leg of the bundle 1 and the smaller leg portions ofthe bundles 2, 3 and 4. Without the windings of the transformer arelocated two legs 6, similar to each other, and two other legs 7 whichare similar to each other. The legs 6 and 7 are parallel to the centerleg 5. The ends of the outer legs are connected to the ends of the leg 5by end connections 6 and 7", respectively. Each leg 6 consists of thewider leg portion of one bundle 2 and the wider leg portions of twobundles 3. Similarly, each leg 7 consists of an end-leg of the bundle 1of E-punchings and the wider legs of two bundles 4. The bundles 1 and 4may be secured together by pins of insulating material (not shown).Similar pins may be employed for securing together the adjacent bundles2 and 3. a

While the punchings composing the core may be proportioned with res ectto each other in Various ways to meet t 1e conditions of particulardesigns, I prefer in some instances to form the E-punehings 1 of thebundle 1, and the U-punchi-ngs 2 and 2 of the bundles 2, as indicated inFigs. 4 to 8, inelusive.

Referring first to Fig. 4, it will be observed that I form one Epunching 1 and two U- punchings 2 and 2 and two end-closing members 11and two end-closing members 12 from stock material with a waste of onlythe three small portions 13. Figs. 5 and 6 illustrate how the twomagnetic circuits of the punchings 1 are completed by the endclosingmembers 11. It will be understood that the punchings shown in Figs. 5and 6 are identical in configuration, the only difference being that thepunchings in one figure are reversed with respect to those in the other.Those skilled in the art will understand that in forming the bundle 1 ofthese punchings some of the superimposed punchings are arranged as shownin Fig. 5 with respect to the bundle, while others are arranged as shownin Fig. 6, thus breaking joints.

The U-punchin s 2 and 2", shown in Figs. 4, 7 and 8, di er from eachother in that the punching 2 has the free ends of its legs beveled inone direction, while the unching 2 has the free ends of its legs beve edin the opposite direction. The two members 12 are similar to each otherand serve as endclosin members for the punchings 2 and 2". It wil beunderstood that the punchings 2 and 2 are made dissimilar in order thatin the assembled punchings the joints may be broken.

By making the ends of the spaces in the punchings 1, 2 and 2 of the formshown in Figs. 4 to 8, inclusive, the magnetic circuit is shortenedslightly. That the corners are cut off of the space between the legs isnot a disadvantage, since it permits the primary windings, which arelocated between the sec ondary windings, to be made longer than thesecondary windings, which is an advanta e, or permits the use of a moreeffective insu ation between the ends of the primary windings and thecore or permits a combination of these advantages. This feature isclearl illustrated by the dotted arrangement of coi s shown in Fig. 5.

By making the end-closing members 11 and 12 with one abutting edge 14parallel to the sides of the core-legs and the other 15 inclinedthereto, with a corresponding arrangement of the ends of the core-legs,the assembly of the end-closing members, which takes place after theremainder of the core is assembled and the windings are ut in place, isfacilitated, since, when the en closing members are forced home, theedges of the endclosing member and abutting edges of the cooperatingcore-legs are wedged together thus forming good joints. With thisconstruction less trouble on account of scratched plates and electricshort-circuits between adjacent laminae produced by fins or projectionsfrom the laminae is experienced than when the joints are parallel to andat right angles to the length of each end iron or connecting piece.Moreover the arrangement of bevel joints with the joints of adjacentlaminae reversed as shown, results in less core loss at the joints thanwith the construction in which the joints are parallel to and at rightangles to the length of the end irons or connecting members. This isbecause the unbroken or unjointed iron at the side of each jointin theconstruction with the bevel joints is less than in the otherconstruction, thus increasing the resistance to and reducing the extentof the eddy currents resulting from the flux which passes from onelamina: into a laminae at the side thereof. It will be understood that alarge portion of the flux instead of passing directly from the leg of aU-punchmg for instance into the corresponding end iron or connectingpiece throu h the joint between them passes first out o the leglaterally into an adacent punching lap ing the joint and then laterallyback into tiie end iron. This is on account of the relatively largeareas of the air-gaps between the leg and adjacent lamime and adjacentlamina. and end iron.

The material 16 cut off of the corners of the outer legs of theE-punching and of! one corner of the wide leg of each punching 2 and 2is not detrimental, since the position of the material cligped offrenders it practically ineffective. lmilarly, the s aces 17 formed inthe middle leg of the punc 'ng 1 do not injuriously affect the magneticproperties of the transformer core. Punchings 3 and 3", 4 and 4", forminthe bundles 3 and 4, respectively, are sirni ar respectively to thepunchings 2 and 2. Their cooperating end-closing members 18 and 19,respectively, are similar to the end-closing members 11 and 12.

In the construction shown in Figs. 1, 2 and 4 to 8 inclusive, the widelegs of the punchings 2 and 2" are each equal in width to each narrowleg of the E-punchings 1 and each s ace between the narrow and wide legsof tlie punchings 2, 2 and 1. Similarly, the yoke ortions of theU-punchings 2 and 2 and t e yokes connecting the narrow and wide legs ofthe punchings 1 are each equal in width to the s aces between the narrowand wide legs. T 1e wide leg of the unching 1 is twice as wide as eachnarrow eg of the unching. The narrow legs of the unchmgs 2 and 2 areeach about two-tlnrds as wide as the wide legs of these unchings.

Referring to Fig. 2, it wil be observed that the width of each bundle 2is equal to the width of the bundle 1. This permits an economical use ofmaterial, since there are twice as many punchings 2 .and 2 formed fromstock by the method illustrated b Fig. 4 as there are of punchings 1 soformedi The construction described permits of a ve economical use ofmaterial. By sub dividing the magnetic circuit of the core, its meanlength is reduced, thus reducing the quantity of iron necessary. Byarranging the windings so that they surround only one portion of thecore, and then making the portion of the core surrounded practicallycircular in outline, the mean length of turn of conductor is made smallfor the amount of magnetic material surrounded and the total amount ofconducting material employed in 136 harm a transformer of a given ratingis made less than has heretofore been employed in transformers in gmeraluse. T 1e transformer construction described, therefore, permits notonly of the use of a small amount of material, but also permits theproportion of the conducting material, such as copper, to the ironemployed to be small. This, of course, is an advantage, since theconducting material, ordinarily copper, costs several times as much asdoes a sinnlar weight of iron.

The mechanical construction of the core described is good. The bundle ofE-punchings forms a rigid member to which the remaining portion of thecore may be mechanically connected in any suitable manner. The arranement of the bundles permits the central Ieg to be made substantiallycircular in outline, with the use of a comparatively t'ew styles andsizes of punchings.

In order to prevent an undue amount of cross-flux in the central legpassing from one bundle into another, the ratio of the part of eachbundle forming a portion of the central leg to the )art formin a portionof an out leg should be practicalIy uniform in the various bundles. Asshown, the outer leg portions of the bundles 2, 3 and 4 are wider thanthe corresponding central leg portions of the bundle in about thesameproportion, while the outer legs of the E-punch1ngs are togetherequal in width to the central leg of the E-punchings. In order topreserve the }')roportion above referred to, I have increased thecross-sectional area of the legs 7 by interleaving between some of theportions of the E-punchmgs forming a part of the legs extra laminae ofmagnetic material, thus increasing the dimension of the legs in adirection at right-angles to the planes of lamination.

In separating the laminae in the manner indieated in Fig. 4, anysuitable cutting mechanism may be employed, for instance, a continuouslyacting roller cutting die may be used.

In the form of my invention shown in Fig. 3-1 have shown an arrangementof the bundles 1,. 2,, 3, and 4,, which gives a section of the centralleg 5 of the core such that the proportion of the length of the coilsurrounding the core to the cross-sectional area of the core surroundedis even higher than with the construction shown in Figs. 1 and 2, andclosely approximates the condition in which the core and coil are trulycircular.v The bundles 1,, 2,, 3,, and 4, may be made up as in the formof my invention first described, or may be built up of laminae assembledin any well-known manner. l

In the form of my invention shown in Fig. 13 bundles of laminae 20, 21,22 and 23 are en'lployed corresponding to the bundles 1, 2, 3 and 4respectively of Figs. 1 and 2. In this form of my invention, however,the bunthe bundles 1, 2 and 4 respectively of the construction shown inFi s. 1 and2 are em ployed; there being no bundles employed correspondinto the bundles 3 of the constructlon of Iigs. 1 and 2.

While the particular forms of my invention hereinbefore described andillustrated possess many excellent properties, it.will be readilyunderstood by those skilled in the art that changes may be made in theforms disclosed without departing from the spirit of my invention, andthat some features of m invention may in some cases be used Without acorresponding use of other features; and I do not wish the claimshereinafter made to be limited to the particular embodiments disclosedmore than is made necessary by the state of the art.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is,

1. In a transformer, a core portion comprising a pair of parallel legsone leg having the corner of one end adjacent the other leg beveled off,and a connecting member having one end beveled off and engaging thebeveled end of the said one leg, the other end of said member beingparallel to and abutting against the side of said other leg.

2. In a magnetic core, a main body of magnetic material laminated in onedirection, two other main bodies of magnetic material laminatedtransversely to the firstmentioned body and located one at each sidethereof with the edges of their laminae abutting against the end laminaeof the firstmentioned main body, the laminae compos- V ing thefirst-mentioned main body being wider than the sides of the other bodiesabutting against it, and one or more bodies of magnetic materialcomposed of laminae 'arallel to the laminae in one of said main odieslocated in the corner spaces between the first-mentioned main body andeach of the said two other main bodies.

3. A transformer core comprising a central leg made up of the middle legof a main bundle of E-shaped laminae and of one leg of each of two mainbundles of U-shaped laminae extending transversely to the E- sha edlaminae from opposite sides of said mi dle leg and one leg of one ormore other bundles of U-shaped laminae each of which is adjacent andlaminated parallel to one of said main bundles.

an E-punchin having its middle leg wider than its 'outsi e legs, twosubstantial similar U-punchings one leg of each ofw "ch is equal 1nwidth to the s ace between the wide leg and either narrow eg of theE-punching, and the necessary end-members, which consists in cuttingfrom stock equal in width to the len th of the legs of the E unchi twicet e Width of a narrow eg of t e E- punching a U-shaped punching from thematerial surrounding each narrow leg of the E-punching and forming theend-members for the U-punchings by cutting a portion off of the freeends of the legs of the U-punchings remote from the center leg of the E-punching and forming the end members for plus the E-punching out ofmaterial cut from the free end of the middle leg of the E-punching. 5.In a transformer, a pair of parallel core ortions and a transverseconnecting portion, lets in the corners between said connecting portionand each parallel portion, and windlngs in the space between said corelegs, said windi comprising low )otential conductors a jacent eachparalle portion and intermediate high potential wlndings.

In witness whereof, I have hereunto set my hand this 7th day ofFebruary, 1906.

JESSE COATES.

Witnesses:

JOHN A. MCMANUS, Jr., HENRY O. WESTENDARP.

